WASHINGTON -- The National Highway Traffic Safety Administration has opened a formal investigation of the 2010 Toyota Prius Hybrid to determine whether the 37,000 vehicles suffer momentary loss of braking capability while traveling over bumpy surfaces.
NHTSA, an agency that is part of the U.S. Department of Transportation, said in a statement that it has received 124 consumer complaints, including four reports of crashes and two of minor injuries.
Some drivers have described the condition as "a brief lag in braking capability or a brief surge while braking," the government's statement said. The reports involve drives "over an uneven road surface, a pothole or a bump," it said.
A Toyota spokeswoman said today the company is aware of NHTSA's initiation of the probe.
"Toyota will cooperate fully with NHTSA's investigation," spokeswoman Cindy Knight said in an e-mail.
"Some customers have experienced inconsistent brake feel when the brakes are applied slowly and the ABS is activated driving over potholes, bumps or slippery road surfaces," she wrote. "The brakes are responding slightly slower than usual, but if the brakes are applied further, the vehicle is controlled."
The braking investigation adds a new headache for Toyota, coming as it does atop a much broader federal probe of problems with unintended acceleration in a host of Toyota vehicles. Toyota Motor Corp. issued recalls of more than 9 million vehicles worldwide in October and January.
The 2004-2009 Prius was included in Toyota's October recall of 3.8 million vehicles for floormat entrapment of the accelerator pedal.
NHTSA so-called "preliminary evaluation" follows interviews with consumers and completed pre-investigative field work, the agency said in a statement. If this evaluation finds adequate evidence, it can be upgraded to an "engineering analysis."
One consumer reported an injury after a series of braking problems on downhills or uneven surfaces -- rather than the bumpy roads cited in NHTSA's statement.
In one case, while approaching an intersection at a modest speed, "when I applied the brakes the car did not slow down as I would have expected," the unnamed consumer reported.
When eventually the vehicle did stop, the airbags went off, injuring his neck and back, the report said. The new Prius sustained $14,000 damage.
In similar incidents in recent months, the vehicle "seems to skip forward or accelerate while braking," the consumer said.